Building codes require builders to make elevators that meet particular safety standards. One such standard is fire rating. A fire rating indicates the amount of time that a particular item can withstand a fire with particular characteristics. For example, an elevator door with a 90-minute fire rating must be tested by being exposed to fire for at least 90 minutes. To pass the rating test, the fire must not spread beyond the elevator door in that 90 minutes. This test is rigorous, and difficult to pass. Previously, glass elevators were unable to pass a 90 minute fire-rating test because the materials, including the glass, could not withstand a 90 minute fire.
One aspect of the fire-rating test is a hose stream test, which tests the strength of the door by spraying water from a fire hose at the door under high pressure. The hose stream test is administered immediately after or within 3 minutes of the 90 minute fire endurance test. Water is sprayed onto the doors from 20 feet away using a 2.5″ hose with a 1⅛″ tip at 30 PSI (pounds per square inch) minimum, subjecting the doors to impact, erosion, and thermal shock.